The fallout from the helmet hits on Carolina Panthers quarterback Cam Newton continues.

The N.F.L. fined two Denver Broncos defenders who hit Newton in the head during their season-opening game last Thursday, according to a league official.

Newton was hit in the head four times in the game; the Broncos were penalized one of those times. The league said the next day that more penalties should have been assigned.

This week, the league fined Broncos safety Darian Stewart $18,231 for his hit on Newton late in the game. A penalty on Stewart was called, but it was offset by a penalty called on the Panthers. Broncos linebacker Brandon Marshall was fined $24,309 for hitting Newton in the head in the third quarter, though no penalty was called on that play.

The hits started a fresh debate about whether the league was doing enough to reduce head trauma in the game, and the fines came on the heels of an announcement by the N.F.L. that it would spend an additional $100 million on technological developments and research aimed at preventing, diagnosing and treating head trauma.

Despite the introduction of penalties against teams that keep players in the game after a head hit when they ought to be examined, Newton was never taken off the field and examined.

The league said doctors on the sideline and in the press box had looked at video and determined that he exhibited no signs of a concussion.

After the game, Newton refused to blame the officials but admitted that “it’s not fun to get hit in the head.”

A version of this article appears in print on , on Page B12 of the New York edition with the headline: N.F.L. Fines Two Broncos for Head Hits on Newton. Order Reprints | Today’s Paper | Subscribe